Hi all,
if anyone is still interested : I managed to install 10.8.2 on a x301 variant :
it's an Asus F301A-RX229H ivy bridge with Intel Pentium 2020M and integrated Intel HD Graphics (a kind of 2500).
There's no way to have the Bios recognize a bootloader on a mac GPT partitioned disk. UEFI boot works properly with Windows GUID/GPT though... Anyway, what I did was use Unibeast USB 10.8.2 (modded to be able to install to an MBR disk). Be sure you don't create an UEFI Unibeast USB device, otherwise it will require a GPT/UEFI disk to install to. So begin with initializing your usb device as MBR, and then create your unibeast installer on it.
Then all I did was to lock the HD audio device in bios during the install, and disable USB legacy. USB xhci has to be set to "auto" or "enabled" in bios for USB3 to work properly. After that, everything went really easilly : installed to disk, rebooted from unibeast-usb selecting the installed disk to boot from, finished Osx configuration, manually created extra folder, copied boot.plist from unibeast usb, and ran Multibeast :
only selected fakesmc, Nullcpu, PS2, RTL81xx, Disk trim (since I replaced my disk with a SSD) and chimera V1.11 with chameleon 2 default theme. (Didn't use no easybeast or any automated multibeast option).From there I could reboot without Unibeast USB device.
I also installed voodoohda, smartpad elan (thanks to Jacob !) and Voodoo battery. I had to add PCIRootUID=0 GraphicsEnabler=Yes and Graphics Mode = 1366x768x32 in my boot.plkist to have the graphics recognized by chimera and the proper framebuffer injected for the HD2500 mobile to (almost) work : no QE/CI obviously.
I still have to investigate the dsdt thing to try and improve boot time (still about 40 secs on my ssd with kernelcache enabled). I won't lose time on trying to get the Wireless to work, and hope someone may find a solution to enable the little graphics acceleration abilities of the HD2500 (mostly to get OpenGL video to work).
I'm also dual booting Win8, which was installed before Osx (created the MBR disk with win8 usb installer, and also the partition destined to osx, which I later erased to HFS with unibeast at the beginning of the installation process).
Hope this helps. Again, if anyone has a clue on how to get QE/CI, you're welcome ! Cheers.